ATOMIC NUMBER : number of protons in an atom hence number of positive charges. It also determines what element the atom is. ATOMIC MASS : protons plus neutrons. These compose the bulk of the mass of the atom. To find how many neutrons are in any atom, subtract the atomic number (protons) from the atomic mass. Electron number = Proton Number in a neutrally charged atom. Atomic Mass – Atomic Number = Number of neutrons
n. An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons.
Bohr Theory states that electrons orbit the nucleus in layers called “shells.” The electrons in the outermost shell react with other atoms to create chemical bonds.
Electron shells are like spaces in a unique PARKING GARAGE. Lower levels must be filled with cars (electrons) before the next level can be occupied.
Example:If the nucleus were the size of a basketball the nearest electron shell would be about 8 miles away. The number of neutrons and protons in the nucleus of any atom determines the atoms chemical and physical characteristics. What does this tell you about the composition of any atom?
The number of parking levels and spaces can be determined by the number of electrons the atom has. Example: H has 1 electron in the first shell. Ca has 2 in the first shell, eight in the second shell, eight in the third shell, and two in the fourth shell. +1 Open Parking Space Electron Mobile
It may not be But let’s park some cars (electrons) in the following elements: B, O, Fe, Al, K, N, C
Sometimes atoms gain or lose electrons in the outermost shell creating an atom with a positive or negative charge.
2NH 3 + 2NaOCl 2NaONH 3 + CL 2
The Pain, the Pain! To understand the affects chlorine gas has on the body, we need to first understand the chemical properties of chlorine. Particularly its valence, or number of chemical bonds chlorine can form. Chlorine is in the 7th group of the A type elements (A type elements are all those except for the Transition Metals, the columns between the column headed by lithium and the column headed by boron on the periodic table.). This means that it has 7 electrons in its outer electron (or valence) shell.
The Octet Rule states that all elements try to fill in their outer electron shell until they have eight electrons (When a chemical has 8 electrons in its outer shell, it is then stable; the Noble Gases are excellent examples ).
So, as it is so close to having 8 electrons in it's outer shell, it literally rips other atoms apart to get them. This is what happens to your respiratory system when you inhale chlorine gas. The gas literally rips apart your nasal passages, trachea, and lungs, by taking electrons out of the atoms that make up your cells. Obviously, chlorine gas causes a very painful death.
Ions in solution make something acidic or basic. H ions indicate an acid solution such as HCl. + Polyatomic ions such as (OH) hydroxide indicates a base. -
Any ion with a positive charge such as H.
Any ion with a negative charge such as Chlorine.
All ionic compounds form crystals. No exceptions. Salts like to form crystals because when you have a bunch of little electrical positive and negative charges all stuck together, they like to bunch into little stacking groups called “unit cells.”
Ionic compounds tend to have high melting and boiling points. And I mean very, very high. Try melting a block of salt with a torch and you will know what I mean.
Ionic compounds are very HARD & BRITTLE. They simply don’t want to bend so they break. Ionic compounds conduct electricity when they dissolve in water. If we take salt and dissolve it in water, the polar nature of the water molecules pull the positive and negative charges apart.
Most ionic compounds have two word names. The first word is the name of the “cation” and the second word is the name of the “anion.” The best way to go about naming ionic compounds is to take a look at the formula, use your periodic table and figure out the names of the cation and the anion. Example: NaCl or BaCl 2 or H 2 SO 4
If the anion has only one atom in it, then the name of the anion is taken off and “-ide” is added to the end. Thus oxygen becomes “oxide” and sulfur become “sulfide.” If the anion is polyatomic, look up the name on the back of the periodic table. These have to be memorized. -SO 4 -PO 4 -NO 3